Several Windows related cleanups:
* Removed a #define from pyconfig.h. The macro was already defined a few lines higher.
* Fixed path to tix in the build_tkinter.py script
* Changed make_buildinfo.c to use versions of unlink and strcat which are considered safe by Windows (as suggested by MvL).
* Removed two defines from pyproject.vsprops that are no longer required. Both are defined in pyconfig.h and make_buildinfo.c doesn't use the unsafe versions any more (as suggested by MvL).
* Added some more information about PGO and the property files to PCbuild9/readme.txt.

Are you fine with the changes, Martin?
diff --git a/PCbuild9/build_tkinter.py b/PCbuild9/build_tkinter.py
index d76ea26..3e24d00 100644
--- a/PCbuild9/build_tkinter.py
+++ b/PCbuild9/build_tkinter.py
@@ -14,7 +14,7 @@
 
 TCL = "tcl8.4.16"
 TK = "tk8.4.16"
-TIX = "Tix8.4.0"
+TIX = "tix-8.4.0"
 #TIX = "Tix8.4.2"
 ROOT = os.path.abspath(os.path.join(here, par, par))
 NMAKE = "nmake /nologo "
@@ -53,6 +53,7 @@
 
     # TIX
     if True:
+        # python9.mak is available at http://svn.python.org
         os.chdir(os.path.join(ROOT, TIX, "win"))
         if clean:
             system(NMAKE + "/f python9.mak clean")